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Basis of Presentation - Additional Information (Detail) | Jun. 30, 2014
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Basis of Presentation [Line Items] |
Minimum percentage of taxable income distribution to shareholders to be taxed as a REIT | 90.00%

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- Details
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Namespace Prefix: | rwt_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Minimum Percentage of Taxable Income Distribution to Shareholders + References No definition available. + Details
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Namespace Prefix: | rwt_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant